1. Field of the Invention
The present invention relates to a method of and an apparatus for pressure slip casting of pottery articles such as sanitary ware.
2. Description of the Relevant Art
As disclosed in Japanese Laid-Open Patent Publication No. 63(1988)-31709, for example, there is known a pressure slip casting apparatus in which a slip is poured into a mold placed horizontally on a mold table, and after a desired shaped article is produced in the mold, the excess slip is discharged from the mold. According to the disclosed pressure slip casting apparatus, the assembled mold is clamped vertically and laterally and placed horizontally on the mold table, and then the slip is poured into the mold and the excess slip is poured from the mold after the desired product is formed in the mold.
The mold has a slip inlet/outlet hole defined in a lower portion thereof. When the slip is introduced through the slip inlet/outlet hole into the molding space or cavity in the mold, air in a region near the inlet/outlet hole tends to be trapped in the slip. Since the air trapped in the slip cannot easily escape from the slip, the article produced in the mold is highly likely to contain unwanted cavities therein. In order to prevent air from being trapped in the slip, the slip has to be poured into the mold at a low speed. Furthermore, if the bottom of the molding cavity in the mold is flat, then the excess slurry cannot easily be discharged from the mold and it takes a long period of time to pour the excess slurry from the mold after the desired ware is formed in the mold. Therefore, the time required to mold a desired shaped product is long and the rate of production of such shaped articles is low.